For the purposes of this Application the term “boat” shall be used and shall be construed to include all waterborne vessels including but not necessarily limited to: boats, ships, yachts, barges, canoes, kayaks, submarines, catamarans, trimarans, etc.
A common feature of traditional boats, is that they are based on the unit-body principle, that is, a hull-bottom with a single continuous skin, resting partially submerged at the surface of the water and displacing a single coherent body of water. Multihull boats (catamarans and trimarans) employ 2 or 3 respectively of such unit-body hulls, spaced apart from each other and held in juxtaposition by shared, rigid deck-beams. Submarines incorporate a completely continuous skin (monocoque) and operate either fully or partially submerged.
A major undesirable characteristic of boats is their predisposition to roll (side-to-side) and to pitch (fore-and-aft) under the influence of wind and/or waves and/or internal movement of weighty objects. This undesirable motion is exacerbated by the fabrication of tall and weighty superstructures, including: cabins, flying-bridges, masts, sails and rigging, to boat hulls. In severe or extreme situations, this predisposition has been the cause of countless loss of lives and boats. Many, varied devices have been, and continue to be employed in the effort to reduce the rolling/pitching actions, and to so produce a boat hull that is more stable and consequently more safe and more comfortable. Among these devices, may be listed:—                In-Hull Ballast: Heavy weights (stones/metal/water), stored inside the bottom of the boat hull. These bring the various penalties of: a) substantially increasing the weight (and displacement) of the boat; b) reducing the speed potential of the boat; c) increasing the power-requirement to propel the boat; d) increasing the mechanical stresses on the hull structure; e) very often requiring that this heavy ballast be moved from one side of the hull to the other, in order to compensate for the boat's changing aspect to the prevailing wind.        Ballasted Keels: Heavy weights (lead/steel/concrete) attached at some distance below the outer skin of the boat hull. These are more efficient than, but mainly present the same penalties as, the in-hull ballast described above. In both cases, a single Centre of Gravity (CG), set some vertical distance away from the virtual pivot established by a single Centre of Buoyancy (COB), acts to generate a pendulum-effect.        Powered Stabilizers: Generally lateral fins protruding from the underwater sides of a boat hull, with motions timed to somewhat counteract the rolling/pitching action of the boat. These bring the penalties of:—a) increased underwater drag on the hull; b) collision hazard with flotsam; c) significant power requirement for their operation; d) significant capital cost and maintenance requirement of complex machinery; e) weight addition to the boat; g) compromise in the watertight integrity of the hull because of their through-hull assembly.        “Flopper-Stoppers”: Discs or planks of large surf area, hung horizontally below the water surface, on both sides of a boat hull and using their resistance to uplift through the water, to counteract the rolling action of the boat. These bring the penalties of: a) being useable only when the boat is at anchor; b) requiring active effort for their deployment/recovery at every anchor/off-anchor activity; c) requiring significant storage space whenever the boat is in-transit.        Increased Beam: Increasing the beam (width) of a boat hull generates an inherent increase in its lateral stability. This however brings the penalties of: a) decrease in streamlining and commensurate increase in drag (resistance) through the water and air; b) increased volume & weight & displacement for a given length of boat; c) much greater difficulty in recovery from a capsize situation.        Increased Floatation at Hull Ends: This is usually accomplished by one or more of the following devices:—                    i) Significant flaring (widening) of the bow sections of the hull.            ii) Keeping the bow and stern sections of the hull substantially empty or very lightly loaded.            iii) Bulbous-Bow: the fabrication of a substantial, elongated bulb protruding forward from the underwater section of the hull bow.            iv) Longitudinal centralization of a major weight components (engines, fuel tanks, water tanks) within the hull.            Singly or in combination, these devices present the penalties of: a) having principal effect mainly against the pitching and much less so against the rolling tendency of the boat; b) significantly increased water-resistance (drag) at the bow of the boat; c) sacrifice of otherwise useable interior space within the boat.                        Multihulls: Conventional catamarans (2 hulls) and trimarans (3 hulls) do present the major advantage of significantly superior lateral stability versus monohulls of similar length. This benefit however, comes with the penalties of:—a) substantially increased beam (width) of the whole boat (typically one-half of the overall length of the boat); b) increased windage since the boat superstructure is so much more voluminous and more difficult to streamline; c) requiring almost double the docking-space as a monohull of similar length; d) unfavourable aesthetics to most boat-owners; e) significantly increased cost of manufacture; f) significantly increased mechanical stresses at the interconnecting points; g) sensitivity to weight-loading; h) sensitivity to wave-slap under the bridge(s) connecting the individual hulls; i) difficulty in road-trailering because of their substantial width; j) susceptibility to pitchpoling and to diagonal-capsize; l) extreme difficulty in recovering from a capsize situation.        
What is pursued by all of the devices described above, is a boat hull of significantly enhanced, inherent stability, fore-and-aft as well as side-to-side. This desired hull should ideally incorporate and enabling device that is:—                Simple and un-complex in design & fabrication.        Inexpensive to manufacture.        Passive rather than active in operation.        Without most or all of the various penalties noted in the foregoing.        